U.S. patent application number 10/863295 was filed with the patent office on 2004-11-25 for hearing aid system and hearing aid method.
Invention is credited to Kobayashi, Toshimitsu, Koike, Takuji, Wada, Hiroshi.
Application Number | 20040234092 10/863295 |
Document ID | / |
Family ID | 30767939 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040234092 |
Kind Code |
A1 |
Wada, Hiroshi ; et
al. |
November 25, 2004 |
Hearing aid system and hearing aid method
Abstract
Sound input to a microphone is converted into an electrical
signal and the electrical signal is amplified by an amplifier. The
amplified electrical signal is supplied to a primary coil as an
alternating current. Thus, a magnetic field around the primary coil
varies with time and a secondary coil generates an induced
electromotive force. A vibrating coil is supplied with current
generated by the induced electromotive force and thus an induced
magnetic field is generated around the vibrating coil. The
vibrating coil provided on the surface of an eardrum is vibrated by
interaction between the induced magnetic field and a magnetostatic
field generated by a permanent magnet.
Inventors: |
Wada, Hiroshi; (Sendai-Shi,
JP) ; Koike, Takuji; (Chofu-Shi, JP) ;
Kobayashi, Toshimitsu; (Sendai-Shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
30767939 |
Appl. No.: |
10/863295 |
Filed: |
June 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10863295 |
Jun 9, 2004 |
|
|
|
PCT/JP03/02361 |
Feb 28, 2003 |
|
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Current U.S.
Class: |
381/331 ;
381/328; 381/401 |
Current CPC
Class: |
H04R 2225/023 20130101;
H04R 25/554 20130101; H04R 25/606 20130101 |
Class at
Publication: |
381/331 ;
381/328; 381/401 |
International
Class: |
H04R 025/00; H04R
009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 2002 |
JP |
2002-215762 |
Claims
What is claimed is:
1. A hearing aid system provided from an external ear region to an
eardrum, comprising: a current generator which generates current
based on an input external sound; a first coil which induces
variations in magnetic field with time based on the current; a
second coil which generates an induced electromotive force based on
the variation in magnetic field with time; a magnetic field
generator which faces the eardrum; and a vibrating coil
electrically connected to the second coil and provided on the
eardrum, which generates a magnetic field whose polarity varies
with the electromotive force and vibrates by interaction between
the magnetic field whose polarity varies and a magnetic field
generated by the magnetic field generator.
2. The hearing aid system according to claim 1, wherein the
vibrating coil is adhered to a surface of the eardrum facing the
external ear region using one of oil and a clip.
3. The hearing aid system according to claim 1, wherein a portion
that contacts a human body is coated with biocompatible insulating
materials.
4. The hearing aid system according to claim 1, wherein the
magnetic field generator is located in the external ear region
close to a middle ear region.
5. The hearing aid system according to claim 1, wherein the
vibrating coil weighs 20 mg or less.
6. The hearing aid system according to claim 1, wherein the
vibrating coil is shaped like a disk.
7. The hearing aid system according to claim 1, wherein a distance
between the magnetic field generator and the vibrating coil is
controlled to adjust intensity of the induced magnetic field.
8. The hearing aid system according to claim 1, wherein the
magnetic field generator is a permanent magnet.
9. A hearing aid method comprising: generating an alternating
current based on an external sound input from sound input means
provided in an external ear region; causing the alternating current
to flow through a first coil to induce variations in magnetic field
with time; generating an induced electromotive force from a second
coil based on the variations in magnetic field with time; causing a
vibrating coil provided on an eardrum to generate an induced
magnetic field whose polarity varies based on the induced
electromotive force; and vibrating the vibrating coil by a
magnetostatic field generated by a magnet that faces the eardrum
and the induced magnetic field generated by the vibrating coil,
thereby vibrating the eardrum.
10. The hearing aid method according to claim 9, wherein the
vibrating coil is adhered to a surface of the eardrum facing the
external ear region using one of oil and a clip.
11. The hearing aid method according to claim 9, wherein a portion
that contacts a human body is coated with biocompatible insulating
materials.
12. The hearing aid method according to claim 9, wherein the magnet
is located in the external ear region close to a middle ear
region.
13. The hearing aid method according to claim 9, wherein the
vibrating coil weighs 20 mg or less.
14. The hearing aid method according to claim 9, wherein the
vibrating coil is shaped like a disk.
15. The hearing aid method according to claim 9, wherein a distance
between the magnet and the vibrating coil is controlled to adjust
intensity of the induced magnetic field.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation Application of PCT Application No.
PCT/JP03/02361, filed Feb. 28, 2003, which was not published under
PCT Article 21(2) in English.
[0002] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2002-215762,
filed Jul. 24, 2002, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to a hearing aid system and a
hearing aid method that uses an electromagnetic coil to vibrate a
vibrating coil rested on the surface of an eardrum.
[0005] 2. Description of the Related Art
[0006] A hearing aid is an apparatus that collects and amplifies a
sound such that the hearing impaired can easily catch the sound.
Currently used hearing aids can largely be divided into two types.
One is an earphone type hearing aid that is generally popularized.
This type of hearing aid is located in an external ear region to
amplify and output an external sound and vibrate an eardrum by
aerial vibration. The earphone type hearing aid is of, for example,
a portable earphone radio type, a behind-the-ear type, and an
external-auditory-meatus insertion type such as an earplug.
[0007] The other is an artificial middle ear type hearing aid in
which a vibrator such as a piezoelectric device and a permanent
magnet is directly attached to auditory ossicle and vibrated. This
type of hearing aid is not influenced by acoustic characteristics
of an external auditory meatus and thus can provide a high-quality
sound.
[0008] However, the hearing aides of the above types have the
following problems.
[0009] The earphone type hearing aid is placed on an external
auditory meatus that is narrowed and shaped complicatedly. It is
thus difficult to achieve characteristics of correctly amplifying
sound pressure to a high audio frequency. If a passage through
which sound is transmitted is a complicated, tube-shaped one such
as an external auditory meatus, resonance and interference occur.
Sound transmitted through the hearing aid therefore differs from a
natural sound.
[0010] The artificial middle ear type hearing aid necessitates an
"invasion" of a human body to attach a vibrator. Specifically, part
of a skull should be shaved and an auditory ossicle of a middle ear
should be removed. An emotional and physical load on a user
therefore increases.
BRIEF SUMMARY OF THE INVENTION
[0011] The present invention has been developed in consideration of
the above situation and its object is to provide a hearing aid
system and a hearing aid method capable of achieving
characteristics of correctly amplifying sound pressure even in a
high audio frequency without any invasion of a human body.
[0012] A hearing aid system according to a first aspect of the
present invention, which is provided from an external ear region to
an eardrum, comprises a current generator which generates current
based on an input external sound, a first coil which induces
variations in magnetic field with time based on the current, a
second coil which generates an induced electromotive force based on
the variation in magnetic field with time, a magnetic field
generator which faces the eardrum, and a vibrating coil
electrically connected to the second coil and provided on the
eardrum, which generates a magnetic field whose polarity varies
with the electromotive force and vibrates by interaction between
the magnetic field whose polarity varies and a magnetic field
generated by the magnetic field generator.
[0013] As a second aspect of the present invention, in the hearing
aid system according to the first aspect, the vibrating coil is
adhered to a surface of the eardrum facing the external ear region
using one of oil and a clip.
[0014] As a third aspect of the present invention, in the hearing
aid system according to the first aspect, a portion that contacts a
human body is coated with biocompatible insulating materials.
[0015] As a fourth aspect of the present invention, in the hearing
aid system according to the first aspect, the magnetic field
generator is located in the external ear region close to a middle
ear region.
[0016] As a fifth aspect of the present invention, in the hearing
aid system according to the first aspect, the vibrating coil weighs
20 mg or less.
[0017] As a sixth aspect of the present invention, in the hearing
aid system according to the first aspect, the vibrating coil is
shaped like a disk.
[0018] As a seventh aspect of the present invention, in the hearing
aid system according to the first aspect, a distance between the
magnetic field generator and the vibrating coil is controlled to
adjust intensity of the induced magnetic field.
[0019] As an eighth aspect of the present invention, in the hearing
aid system according to the first aspect, the magnetic field
generator is a permanent magnet.
[0020] A hearing aid method according to a ninth aspect of the
present invention, comprises generating an alternating current
based on an external sound input from sound input means provided in
an external ear region, causing the alternating current to flow
through a first coil to induce variations in magnetic field with
time, generating an induced electromotive force from a second coil
based on the variations in magnetic field with time, causing a
vibrating coil provided on an eardrum to generate an induced
magnetic field whose polarity varies based on the induced
electromotive force, and vibrating the vibrating coil by a
magnetostatic field generated by a magnet that faces the eardrum
and the induced magnetic field generated by the vibrating coil,
thereby vibrating the eardrum.
[0021] As a tenth aspect of the present invention, in the hearing
aid method according to the ninth aspect, the vibrating coil is
adhered to a surface of the eardrum facing the external ear region
using one of oil and a clip.
[0022] As an eleventh aspect of the present invention, in the
hearing aid method according to the ninth aspect, a portion that
contacts a human body is coated with biocompatible insulating
materials.
[0023] As a twelfth aspect of the present invention, in the hearing
aid method according to the ninth aspect, the magnet is located in
the external ear region close to a middle ear region.
[0024] As a thirteenth aspect of the present invention, in the
hearing aid method according to the ninth aspect, the vibrating
coil weighs 20 mg or less.
[0025] As a fourteenth aspect of the present invention, in the
hearing aid method according to the ninth aspect, the vibrating
coil is shaped like a disk.
[0026] As a fifteenth aspect of the present invention, in the
hearing aid method according to the ninth aspect, a distance
between the magnet and the vibrating coil is controlled to adjust
intensity of the induced magnetic field.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0027] FIG. 1 is a schematic diagram illustrating a configuration
of a hearing aid system according to an embodiment of the present
invention.
[0028] FIG. 2 is a schematic diagram illustrating a configuration
of the hearing aid system according to the embodiment of the
present invention.
[0029] FIG. 3 is a graph showing a relationship between audio
frequency and sound pressure in a cochlea when vibrating coils 21
that differ in mass are rested on the surface of an eardrum and an
exciting force corresponding to a sound pressure of 80 dBSPL is
applied thereto.
DETAILED DESCRIPTION OF THE INVENTION
[0030] An embodiment of the present invention will now be described
with reference to the drawings. In the following descriptions, the
components having substantially the same function and configuration
are denoted by the same reference numerals and their descriptions
are repeated only when the need arises.
[0031] FIGS. 1 and 2 are schematic diagrams each showing a
configuration of a hearing aid system according to an embodiment of
the present invention. As shown in FIGS. 1 and 2, the present
hearing aid system includes a microphone 11, an amplifier 13, a
primary coil 15, a secondary coil 17, a permanent magnet 19 and a
vibrating coil 21.
[0032] The microphone 11 receives an external sound such as a
conversational sound and converts it into an electrical signal.
[0033] The amplifier 13 amplifies the electrical signal, into which
the sound is converted by the microphone 11, to a given intensity
level. The intensity of the amplification can be controlled to have
an arbitrary level.
[0034] The electrical signal amplified by the amplifier 13 flows
through the primary coil 15. The primary coil 15 therefore
generates an induced magnetic field as the electrical signal varies
with sound.
[0035] The secondary coil 17 generates an induced electromotive
force as the magnetic field generated by the primary coil 15
varies. In the present embodiment, though the secondary coil 17 is
not limited to a specific shape, it is shaped to surround the
primary coil 15 in order to increase the density of magnetic flux
going through the secondary coil 17 and generate an induced
electromotive force with efficiency.
[0036] The permanent magnet 19 is supported by a given frame and
fixed on an external auditory meatus. As will be described later, a
magnetostatic field generated by the permanent magnet 19 serves as
a driving source for vibrating the vibrating coil 21. In order to
bring efficiency to the vibration and prevent a shift in position
due to the contact of the permanent magnet 19 with a user's finger
or the like, the permanent magnet 19 favorably faces the vibrating
coil 21 as close as possible to an eardrum (or in an external
auditory meatus as close as possible to a middle ear).
[0037] The vibrating coil 21 is a lightweight coil that is adhered
to the surface of an eardrum facing an external auditory meatus
using oil. According to inventors' experiment, if the coil weighs,
e.g., 20 mg or less, it can considerably decrease in its inertia
and generate a nearly natural sound (see FIG. 3). The vibrating
coil 21 can be provided with a clip made of shape memory alloy
which holds a region spanning the surface of an eardrum facing an
external auditory meatus and part of an auditory ossicle.
[0038] The vibrating coil 21 is not limited to a specific shape. It
is however desirable that the vibrating coil 21 be shaped like a
disk in order to increase the internal magnetic field of the
vibrating coil 21 such that the coil 21 can generate a greater
exciting force, vibrate minutely at high speed and ensure dynamic
stability.
[0039] It is desirable that a portion of each of the
above-described components, which is likely to contact user's skin,
be coated with biocompatibility materials in order to prevent the
skin from being irritated. It is also desirable that a portion of
each of the components through which current flows be coated with
leakage current preventing materials in order to prevent current
from leaking to tissues from a living body. For example, silicon is
material that meets the above two conditions.
[0040] There now follows an explanation of the operating principle
of the present hearing aid system.
[0041] In FIG. 2, when the microphone 11 receives an external
sound, the sound is converted into an electrical signal. The
amplifier 13 amplifies the electrical signal to a given intensity
level.
[0042] The amplified electrical signal is supplied to the primary
coil 15 as an alternating current. When the alternating current
flows through the primary coil 15, a magnetic field around the
primary coil 15 varies with time to change a magnetic flux that
goes through the secondary coil 17. Consequently, the secondary
coil 17 generates an induced electromotive force that is
proportionate to the variations of the magnetic field with
time.
[0043] The vibrating coil 21 electrically connected to the
secondary coil 17 is supplied with current caused by the induced
electromotive force generated from the secondary coil 17. When the
current caused by the induced electromotive force flows through the
vibrating coil 21, an induced magnetic field due to the induced
electromotive force is generated around the vibrating coil 21. The
vibrating coil 21 generates a driving force that excites an eardrum
by interaction between the induced magnetic field and the
magnetostatic field formed by the permanent magnet 19.
[0044] More specifically, sound input to the microphone 11 is
transmitted to the vibrating coil 21, which is provided on the
surface of an eardrum as an exciting force, through the alternating
current supplied to the primary coil 15, the induced electromotive
force generated from the secondary coil 17, and the interaction
between the induced magnetic field caused by the induced
electromotive force and the magnetostatic field of the permanent
magnet 19. The external sound can thus be transmitted to the
eardrum as vibration, which functions as a hearing aid.
[0045] The above configuration can produce the following
advantage.
[0046] The present hearing aid system 10 employs the lightweight
vibrating coil 21. Since, therefore, the inertia of the vibrating
coil 21 is small, the vibration can efficiently be transmitted to
the surface of an eardrum even though an external sound in a high
audio frequency band is input.
[0047] FIG. 3 is a graph showing a relationship between audio
frequency and sound pressure in a cochlea when vibrating coils 21
that differ in mass (20 mg, 40 mg, 100 mg) are rested on the
surface of an eardrum and an exciting force corresponding to a
sound pressure of 80 dBSPL is applied thereto. Referring to FIG. 3,
almost the same sound pressure as in the normal state with no
vibrating coils 21 (thick solid line in the figure) can be obtained
if the vibrating coils 21 are reduced in weight.
[0048] The present hearing aid system 10 is so configured that the
lightweight vibrating coils 21 are adhered by oil or the like and
the microphone 11, permanent magnet 19, etc. are placed from an
external ear region and an eardrum. Hence, these components can
easily be attached without performing any operation for invasion of
a human body. As a result, growing infants to aged persons can use
the hearing aid system at ease.
[0049] A conventional earphone type hearing aid amplifies sound
input to a microphone and transmits the amplified sound directly to
an eardrum. In this configuration to vibrate the eardrum directly
by sound waves, resonance and interference of the sound waves are
likely to occur in an external auditory meatus that is narrowed and
shaped complicatedly. Consequently, there is a case where a natural
sound is not faithfully reproduced from the sound transmitted
through the hearing aid. In the conventional earphone type hearing
aid, the earphone and microphone are close to each other and thus
the microphone is likely to receive sound again from the earphone
to cause a howl.
[0050] In the present hearing aid system 10, an eardrum is vibrated
by vibrating the vibrating coil 21 provided on the surface of the
eardrum by magnetic interaction using electromagnetic induction.
Therefore, the hearing aid system 10 neither causes a phenomenon
such as resonance and interference of sound waves and a howl nor
subjects to acoustical constraints, unlike the conventional hearing
aid. A natural sound of high quality can thus be reproduced
faithfully.
[0051] The present hearing aid system 10 also amplifies an
electrical signal into which an input sound is converted, generates
magnetic interaction using electromagnetic induction in response to
the amplified electrical signal, and vibrates the vibrating coil 21
provided on the surface of an eardrum. By controlling the degree of
amplification of the electrical signal, the distance between the
vibrating coil 21 and permanent magnet 19 and the like, a greater
magnetic interaction can be generated and so can be a driving force
for vibrating the vibrating coil 21. Since the hearing aid system
has such characteristics and does not subject to the above
acoustical constraints, it can provide highly mixed
hearing-impaired persons with a clear sound.
[0052] The present hearing aid system 10 is a simple, low-cost
apparatus and thus can provide many people with good communication
in an aging society that is expected in the near future.
[0053] The present invention has been described based on the
embodiment thereof. Persons with ordinary skill in the art can
think of various changes and modifications within the category of
the concept of the present invention. It is understood that the
changes and modifications fall within the scope of the present
invention. Various changes and modifications can be made without
departing from the scope of the subject matter of the present
invention.
[0054] Embodiments can be combined appropriately as much as
possible and, in this case, an advantage can be obtained from the
combination. The above embodiments contain inventions in various
stages and these inventions can be extracted from appropriate
combinations of a plurality of components disclosed in the
embodiments. Even though some of all the components shown in the
embodiments are deleted, the structure of the remaining components
can be extracted as an invention if the problem of the invention
can be resolved and the advantage of the invention is obtained.
[0055] The present invention can provide a hearing aid system and a
hearing aid method capable of achieving characteristics of
correctly amplifying sound pressure even in a high audio frequency
without any invasion of a human body.
* * * * *